Historically, Istanbul has been the centre of the country's economic life, even after Ankara became Turkey's official capital in 1923.

In 2005 the city's GDP reached $133 billion. Istanbul generates 55 percent of Turkey's trade as well as 21.2 percent of Turkey's gross national product. It contributes 40 percent of all taxes collected in Turkey and produces 27.5 percent of Turkey's national product.

Istanbul houses the Istanbul Stock Exchange (ISE), Turkey's only securities market. Aside from being a popular tourist destination, the city is home to the headquarters of Turkey's largest companies and banks.

The number of high-rises is also growing throughout the city. One of the most important transformations has been the construction of apartment houses, intended to replace the first generation of gecekondu housing. After growing horizontally for decades, the city is now growing vertically.